Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
  #include<bits/stdc++.h>
using namespace std;
int main(){
  int xx[4]={-1,1,0,0};
  int yy[4]={0,0,-1,1};
  int h,w;cin>>h>>w;
  string s[h];
  bool bo[h][w];
  for(int i=0;i<h;i++)for(int j=0;j<w;j++)bo[i][j]=false;
  for(int i=0;i<h;i++) cin>>s[i];
  int cnt=0;
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      if(s[i][j]=='.') cnt++;
    }
  }
  queue<int>qx;
  queue<int>qy;
  queue<int>qn;
  qn.push(0);
  qx.push(0);qy.push(0);
  while(qx.size()>0){
    int x=qx.front();
    int y=qy.front();
    int n=qn.front();
    if(x==w-1&&y==h-1){
      cout<<cnt-n-1<<endl;
      return 0;
    }
    
    qn.pop();
    qx.pop();qy.pop();
    for(int i=0;i<4;i++){
      if(bo[y+yy[i]][x+xx[i]]==false&&y+yy[i]>=0&&y+yy[i]<h&&x+xx[i]>=0&&x+xx[i]<w&&s[y+yy[i]][x+xx[i]]=='.'){
        qx.push(x+xx[i]);qy.push(y+yy[i]);qn.push(n+1);
        bo[y+yy[i]][x+xx[i]]=true;
      }
    }
  }
  cout<<-1<<endl;
}